Sloped screen separator that removes solids from a manure slurry

ABSTRACT

A large percentage of solids are removed from a manure slurry when the slurry is run across a sloped screen separator. The sloped screen on the separator has very small openings. In addition, the separator has a water line with spray heads formed across the sloped screen. The spray heads direct water under pressure onto the sloped screen. Further, the separator controls the air flow through the sloped screen.

RELATED APPLICATIONS

[0001] The present application is a divisional application of U.S.patent application Ser. No. 09/822,898 to Richard Dias filed Mar. 30,2001 entitled “Sloped Screen Separator that Removes Solids from a ManureSlurry” (Atty. Docket No. 024009-0276266; Client Ref. RD-001) and claimspriority therefrom, the contents of which are incorporated herein byreference. The present application is also related to U.S. applicationSer. No. ______ (RD-001-D2; Atty. Docket No. 024009-0300215), entitled“Manure Management System using Sloped Screen Separator,” filedconcurrently herewith and commonly owned by the sole applicant, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a separator and, moreparticularly, to a sloped screen separator that removes solids from amanure slurry.

[0004] 2. Description of the Related Art

[0005] When waste, such as manure, is washed away with a stream of flushwater, a waste or manure slurry is formed. In agriculture, enclosedanimal areas are commonly flushed with water. For example, in the dairyindustry, the alleys in a freestall barn are typically flushed twice aday with water to clean the manure from the alleys.

[0006] The treatment of manure slurry is a difficult and on-goingproblem in many agricultural settings. One approach to treating manureslurry is to fill large settling pits or lagoons with the slurry.Gravity then pulls the larger solids to the bottom. The surface water,which contains fewer solids, is typically pumped to another lagoon,where the process is repeated. The surface water of the last lagoon isthen pumped out to irrigate agricultural lands, such as alfalfa fields,or used again to flush accumulated manure from animal areas.

[0007] This approach, while relatively straightforward, has a number ofdrawbacks. One drawback is that the accumulated solids in the lagoonshave to be periodically removed at a significant expense. Anotherdrawback is that the longer the manure stays in suspension within theslurry, the more nutrients transfer from the solids to the water.

[0008] This loads the water with very high levels of nitrogen,phosphorous, and salts. A high loading, in turn, limits the amount ofirrigation that can be performed, or requires the addition of freshwater to change the loading of the water. A further problem is that asignificant amount of gas, such as ammonia and sulfer, escapes from theslurry in a lagoon, thereby contributing to air pollution.

[0009] A common modification to this approach is to run the manureslurry through a separator to remove as many solids from the slurry aspossible. By removing solids from the slurry, fewer solids are depositedin the lagoons. Reducing the amount of solids that are deposited into alagoon increases the useful life of the lagoon, reduces the loading ofthe water (because solids are removed from the water), and reduces airpollution. One type of separator is a sloped screen separator.

[0010]FIG. 1 shows a cut-away perspective view that illustrates aconventional sloped-screen separator 100, while FIG. 2 shows a side viewof separator 100. As shown in FIGS. 1-2, separator 100 has a back wall110, and first and second side walls 112 and 114 that are connected toback wall 110. Side walls 112 and 114, in turn, have openings 116 and118.

[0011] In addition, separator 100 has a top panel 120 that is connectedto the top ends of side walls 112 and 114, and a lower panel 122 that isconnected to the bottom ends of back wall 110 and side walls 112 and114. Lower panel 122, in turn, has an opening 124.

[0012] Separator 100 also has a ledge 130 that is connected to sidewalls 112 and 114, and a trough 132 that is connected to back wall 110,side walls 112, and ledge 130. Trough 132 has a bottom side 134, and anopening 136 formed in bottom side 134. Separator 100 further includes abaffle 140 that is connected to side walls 112 and 114 over thelongitudinal center of trough 132.

[0013] As further shown in FIGS. 1-2, separator 100 has a front edge 142that is connected to side walls 112 and 114 and lower panel 122, and asloped screen 144 that is connected to side walls 112 and 114, ledge130, and front edge 142. Sloped screen 144 typically has slotted orcircular openings of 1.5 mm (approximately 0.060 of an inch).

[0014] In operation, manure slurry is pumped into trough 132 throughopening 136. Baffle 140 spreads the incoming slurry so that the slurryflows evenly over the edge of ledge 130 onto sloped screen 144. Theslurry flows through screen 144, with screen 144 extracting the largersolids from the slurry.

[0015] Gravity pulls the larger solids extracted by screen 144 down theface of screen 144. The solids accumulate at the bottom of screen 144,and eventually fall off of front edge 142 where the solids are collectedas stackable manure. In the dairy industry, stackable manure has amoisture content of roughly 75-80%.

[0016] One problem with separator 100 is that separator 100 isrelatively inefficient. Experimental results indicate that separator 100removes, at best, approximately 16% of the solids in the slurry. Thus,even though separator 100 removes solids from the slurry, large amountsof solids continue to be added to the lagoons.

[0017] Screens with smaller openings are not utilized because the solidsin the slurry plug the openings. When the openings in the screen becomeplugged, all the slurry pumped into opening 136 of trough 132 runs downthe face of screen 144 and falls off of front edge 142, causing slurryto be pumped into the work yard. The resulting clean up can be asignificant expense. Thus, due to plugging, screens with openings equalto or less than 1.0 mm (approximately 0.040 of an inch) are consideredto be unworkable.

[0018] With separator 100, the slurry falls through screen 144 and iscollected by lower panel 122. The slurry then flows out opening 124where the slurry is gravity fed to a lagoon. The flow of slurry intoopening 124 creates a suction. If openings 116 and 118 were absent orclosed, the suction would pull air through screen 144. The flow of airthrough screen 144, however, pulls and holds solids to screen 144,thereby plugging the openings. Thus, openings 116 and 118 provide an airintake route that eliminates the suction across screen 144 so thatlarger solids can fall down the face of screen 144.

[0019] Screen 144 is also subject to plugging from hot summertimeconditions. When the available slurry has been pumped through separator100, solids to varying degrees remain on the face of screen 144. In hotsummertime conditions, the solids quickly dry. When the slurry is againpumped into separator 100, the initial slurry runs down the face ofscreen 144 and falls off front edge 142 until the moisture in the slurryunplugs the openings.

[0020] One approach to preventing summertime conditions from pluggingscreen 144 is to mist the face of screen 144 when slurry is no longerbeing pumped into separator 100. This can be accomplished by placing awater line with a number of mist heads across the front of screen 144.

[0021] When the water line is connected to a water source underpressure, such as 2.46 kilograms per square centimeter (approximately 35pounds per square inch) to 3.87 kilograms per square centimeter(approximately 55 pounds per square inch), the mist heads output mist inthe range of 2.65 liters per hour (approximately 0.7 gallons per hour)to 4.9 liters per hour (approximately 1.3 gallons per hour). The levelof misting should not cause solids to move down or sheet down the faceof screen 144.

[0022] Thus, although sloped screen separators reduce the volume ofsolids that are deposited into the holding lagoons, there is a need fora separator that removes more solids from the manure slurry.

SUMMARY OF THE INVENTION

[0023] The present invention provides a sloped screen separator. Thesloped screen separator of the present invention includes an inputcompartment that has an input opening and an output ledge. A manureslurry is pumped into the input compartment through the input opening,and flows out over the output ledge. The separator also includes asloped screen that is connected to the output ledge of the inputcompartment. The sloped screen has a plurality of screen openings thateach have a size that ranges from a lower size to an upper size. Thelower size is greater than a size that requires shaking before themanure slurry will fall through the screen openings. The upper size isequal to or less than 1.0 mm. The manure slurry flows out over theoutput ledge onto the sloped screen when the manure slurry is pumpedinto the input compartment.

[0024] The separator further includes a collection compartment that isconnected to the sloped screen. The collection compartment has an airflow opening and a slurry exit opening. The collection compartmentreceives a screened slurry that falls through the sloped screen when themanure slurry is pumped into the input compartment. The screened slurryflows out through the slurry exit opening.

[0025] The separator additionally includes a water pipe that isconnected to the collection compartment. The water pipe extends acrossthe sloped screen. Further, a plurality of spray heads are connected tothe water pipe. The spray heads output a liquid at a rate that rangesfrom equal to or greater than 113 liters per hour to equal to or lessthan 1362 liters per hour per approximately 0.31 meters of the width ofthe screen.

[0026] The separator also includes an air flow controller that isconnected to the collection compartment. The air flow controllercontrols a first volume of air that flows through the sloped screen as aresult of the screened slurry flowing through the slurry exit opening.The air flow controller variably controls a second volume of air thatcan flow into the air flow opening to thereby vary the first volume ofair that is pulled through the sloped screen.

[0027] The present invention also includes a method of removing solidsfrom a manure slurry. The method includes the step of running the manureslurry over a sloped screen. The sloped screen has a plurality of screenopenings that each have a size that ranges from a lower size to an uppersize. The lower size is greater than a size that requires shaking beforethe manure slurry will fall through the screen openings. The upper sizeis equal to or less than 1.0 mm. The method further includes the step ofcollecting a screened slurry that falls through the sloped screen in acollection compartment.

[0028] The method additionally includes the step of spraying the manureslurry with a liquid with sprayers at a rate that ranges from equal toor greater than 113 liters per hour to equal to or less than 1362 litersper hour per approximately 0.31 meters of the width of the screen. Themethod also includes the step of controlling a volume of air that flowsthrough the sloped screen.

[0029] A better understanding of the features and advantages of thepresent invention will be obtained by reference to the followingdetailed description and accompanying drawings that set forth anillustrative embodiment in which the principles of the invention areutilized.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] These and other aspects and features of the present inventionwill become apparent to those ordinarily skilled in the art upon reviewof the following description of specific embodiments of the invention inconjunction with the accompanying figures, wherein:

[0031]FIG. 1 is a cut-away perspective view illustrating a conventionalsloped-screen separator 100;

[0032]FIG. 2 is a side view of separator 100;

[0033]FIG. 3 is a cut-away perspective view illustrating a sloped-screenseparator 300 in accordance with the present invention;

[0034]FIG. 4 is a side view of separator 300 in accordance with thepresent invention;

[0035]FIG. 5 is a front view of separator 300 in accordance with thepresent invention;

[0036]FIG. 6 is a side view of separator 300 illustrating the operationof separator 300 in accordance with the present invention;

[0037]FIG. 7 is a cut-away perspective view illustrating a separator 700in accordance with a first alternate embodiment of the presentinvention;

[0038]FIG. 8 is a cut-away perspective view illustrating a separator 800in accordance with a second alternate embodiment of the presentinvention;

[0039]FIG. 9 is a cut-away perspective view illustrating a separator 900in accordance with a third alternate embodiment of the presentinvention;

[0040]FIG. 10 is a drawing illustrating a manure management system 1000in accordance with the present invention; and

[0041]FIG. 11 is a drawing illustrating a manure management system 1100in accordance with the present invention.

DETAILED DESCRIPTION

[0042]FIG. 3 shows a cut-away perspective view that illustrates asloped-screen separator 300 in accordance with the present invention.FIG. 4 shows a side view of separator 300, while FIG. 5 shows a frontview of separator 300. As shown in FIGS. 3-5, separator 300 has a backwall 310, and first and second side walls 312 and 314 that are connectedto back wall 310. Side walls 312 and 314, in turn, have openings 316 and318, respectively.

[0043] In addition, separator 300 has a top panel 320 that is connectedto the top ends of side walls 312 and 314, and a lower panel 322 that isconnected to the bottom ends of back wall 310 and side walls 312 and314. Top panel 320 can be optionally omitted. Lower panel 322 has anopening 324.

[0044] Separator 300 also has a ledge 330 that is connected to sidewalls 312 and 314, and a trough 332 that is connected to back wall 310,side walls 312 and 314, and ledge 330. Trough 332 has a bottom side 334,and an opening 336 formed in bottom side 334. Separator 300 furtherincludes a baffle 340 that is connected to side walls 312 and 314 overthe longitudinal center of trough 332.

[0045] As further shown in FIGS. 3-5, separator 300 has a front edge 342that is connected to side walls 312 and 314 and lower panel 322, and asloped screen 344 that is connected to side walls 312 and 314, ledge330, and front edge 342. Trough 332 defines an inflow compartment thathas input opening 336 and output ledge 330, while the region betweenback wall 310, side walls 312 and 314, lower panel 322, front edge 342,and sloped screen 344 define an outflow compartment. The outflowcompartment has an air flow opening 316/318 and a slurry exit opening324.

[0046] In accordance with the present invention, sloped screen 344 hasopenings that range from greater than the size where slurry will notflow through the openings without being shaken, which is approximately0.15 mm (approximately 0.006 of an inch), to less than 1.0 mm(approximately 0.040 of an inch). Thus, the present invention utilizesopening sizes that were previously considered to be unworkable.

[0047] In further accordance with the present invention, separator 300includes an air flow controller 350 connected to opening 316, and an airflow controller 352 connected to opening 318. Controllers 350 and 352variably control the volume of air that can flow into openings 316 and318, respectively, to thereby vary the volume of air that is pulledthrough screen 344. For example, if controllers 350 and 352 restrict thevolume of air that can flow into openings 316 and 318 to zero,effectively closing openings 316 and 318, all of the air would be pulledthrough screen 344.

[0048] In additional accordance with the present invention, separator300 also includes a water line 354 that is attached to side walls 312and 314 and positioned across the face of screen 344 about ¼ of the waydown from the top of screen 344. Separator 300 further includes a numberof spaced-apart spray heads 356 that are connected to water line 354.Spray heads 356 are positioned about 0.31 meters (approximately onefoot) from the face of screen 344 (measured along a horizontal planethat passes through spray heads 356).

[0049] The section of water line 354 between side walls 312 and 314 canbe rotatably coupled to the remainder of water line 354 via coupler 358.As a result, the angle at which the water output by heads 356 strikesscreen 344 can be changed by rotating the section of water line 354between side walls 312 and 314. Best results appear to be obtained whenwater strikes screen 344 at a point above spray heads 356, such asroughly an angle of 65° (measured counter clockwise from a horizontalplane passing through spray heads 356).

[0050] Spray heads 356 include two quarter-circle spray heads 360 thatare positioned next to side walls 312 and 314, and a number ofhalf-circle spray heads 362 that are positioned between heads 360. Heads360 can be implemented, for example, with spray head model number S9Qsold by Champion Irrigation Products, while heads 362 can be implementedwith, for example, spray heads model number S9H sold by ChampionIrrigation Products.

[0051] Different arrangements of spray heads can also be used in thepresent invention. For example, rather than using two types of sprayheads, all of the spray heads can be the same. In addition, narrow widthscreens (where width is measured from side wall 312 to side wall 314)can be implemented with only a single spray head.

[0052]FIG. 6 shows a side view of separator 300 that illustrates theoperation of separator 300 in accordance with the present invention. Asshown in FIG. 6, manure slurry 610 is pumped into trough 332 throughopening 336 at a rate of approximately 1703.25 liters per minute(approximately 450 gallons a minute).

[0053] Baffle 440 spreads slurry 610 so that slurry 610 flows evenlyover the edge of ledge 330 onto sloped screen 344 where slurry 610 isthen sprayed by heads 360 and 362. Water line 354 is connected to awater source under pressure, such as in the range of 0.70 kilograms persquare centimeter (approximately 10 pounds per square inch) to 5.27kilograms per square centimeter (approximately 75 pounds per squareinch).

[0054] With a pressure of approximately 3.17 kilograms per squarecentimeter (approximately 45 pounds per square inch), heads 360 output aspray of about 4.9 liters per minute (approximately 1.3 gallons perminute), while heads 362 output a spray of about 8.3 liters per minute(approximately 2.2 gallons per minute).

[0055] The amount of water sprayed on screen 344 can be adjusted bychanging the water pressure, given a spray opening with a fixed size.Less water can be sprayed on a slurry that has a lower number of solids,while more water can be sprayed on a slurry that has a higher number ofsolids. For each 0.31 meters (approximately one foot) of screen width(where width is measured from side wall 312 to side wall 314), water issprayed (approximately evenly) in the range of 1.89 to 22.71 liters perminute (approximately 0.5 to 6 gallons per minute).

[0056] In addition, controllers 350 and 352 reduce the volume of airthat flows through openings 316 and 318 so that a volume of air ispulled through screen 344. A screened slurry 612 falls through screen344, while solids 614 are extracted by screen 344. Gravity pulls solids614 down the face of screen 344. Solids 614 accumulate at the bottom ofscreen 344, and eventually fall off of front edge 342 where the solidsare collected as stackable manure.

[0057] In accordance with the present invention, controllers 350 and 352are set to pull a greater volume of air through screen 344 when theslurry has a lower concentration of solids, and a smaller volume of airthrough screen 344 when the slurry has a higher concentration of solids.

[0058]FIG. 7 shows a cut-away perspective view of a separator 700 inaccordance with a first alternate embodiment of the present invention.Separator 700 is similar to separator 300 and, as a result, utilizes thesame reference numerals to designate the structures which are common toboth separators.

[0059] As shown in FIG. 7, separator 700 differs from separator 300 inthat separator 700 has a plurality of openings 710 on each side wall 312and 314 rather than single openings 316 and 318. Each opening 710, inturn, has a rotatably-connected cover 712. In operation, the volume ofair pulled through screen 344 is determined by the number of openings710 that are open, partially opened, or closed. For example, if all ofthe openings 710 were closed by covers 712, all of the air would bepulled through screen 344.

[0060]FIG. 8 shows a cut-away perspective view of a separator 800 inaccordance with a second alternate embodiment of the present invention.Separator 800 is similar to separator 300 and, as a result, utilizes thesame reference numerals to designate the structures which are common toboth separators.

[0061] As shown in FIG. 8, separator 800 differs from separator 300 inthat separator 800 does not have air flow controllers 350 and 352. Inseparator 800, openings 316 and 318 are formed to be large enough toprevent solids from being pulled into screen 344 as a result of slurryflowing out of opening 324. Separator 800 further differs from separator300 in that separator 800 has openings ranging from about 0.51 mm(approximately 0.020 of an inch), to about 1.78 mm (approximately 0.070of an inch). Experimental results taken with a screen having 0.89 mm(approximately 0.035 of an inch) openings indicate that, although not asdramatic as separator 300, separator 800 also removes more solids thandoes conventional separator 100.

[0062]FIG. 9 shows a cut-away perspective view of a separator 900 inaccordance with a third alternate embodiment of the present invention.Separator 900 is similar to separator 300 and, as a result, utilizes thesame reference numerals to designate the structures which are common toboth separators.

[0063] As shown in FIG. 9, separator 900 differs from separator 300 inthat separator 900 does not have air flow controllers 350 and 352, waterline 354, or spray heads 356. Separator 900 further differs fromseparator 300 in that separator 900 has openings ranging from about 0.51mm (approximately 0.020 of an inch), to less than 1.0 mm (approximately0.040 of an inch). Experimental results taken from separator 900 usingabout 0.89 mm (approximately 0.035 of an inch) openings indicate that asthe percentage of solids in the slurry drops, the size of the openingscan be reduced.

[0064]FIG. 10 shows a drawing that illustrates a manure managementsystem 1000 in accordance with the present invention. As shown in FIG.10, system 1000 includes an initial holding basin 1010, a firstsloped-screen separator 1012, and a pumping system 1014 that pumpsslurry from basin 1010 to separator 1012. Separator 1012, which hasscreen openings of a first size, can be implemented with separators 300,700, 800, or 900. Separator 100 can alternately be used to implementseparator 1012.

[0065] System 1000 further includes a second sloped-screen separator1022 that receives slurry from separator 1012, a lagoon 1030 thatreceives slurry from separator 1022, and a pumping system 1032 that isconnected to lagoon 1030. Separator 1022, which has screen openings of asecond size, can be implemented with separators 300 and 700.

[0066] In accordance with the present invention, separator 1012 hasscreen openings that are larger than the screen openings of separator1022. For example, separator 1012 can have openings of about 0.89 mm(approximately 0.035 of an inch) while separator 1022 can have openingsof about 0.25 mm (approximately 0.010 of an inch). As another example,separator 1012 can have openings of about 1.52 mm (approximately 0.060of an inch) while separator 1022 can have openings of about 0.25 mm(approximately 0.010 of an inch).

[0067] In operation, a flushed manure slurry 1040 is collected inholding basin 1010. Holding basin 1010 need only be large enough to holdthe slurry from a single flushing, although additional capacity would beneeded if back up pumping capacity is unavailable. As a result, holdingbasin 1010 can be small in size.

[0068] Pumping system 1014 then pumps slurry 1040 from basin 1010 intoseparator 1012. Separator 1012 outputs a once-screened slurry 1042 thatis gravity fed into separator 1022, and an amount of stackable solidsthat fall over front edge 342 of separator 1012. Separator 1022 outputsa twice-screened slurry 1044 that is gravity fed into lagoon 1030, andan amount of stackable solids that fall over front edge 342 of separator1022. Pumping system 1032 then pumps twice-screened slurry 1044 out forirrigation, such as for alfalfa fields, or flushing.

[0069]FIG. 11 shows a drawing that illustrates a manure managementsystem 1100 in accordance with the present invention. System 1100 issimilar to system 1000 and, as a result, utilizes the same referencenumerals to designate the structures which are common to both systems.

[0070] As shown in FIG. 11, system 1100 differs from system 1000 in thatsystem 1000 includes a second holding basin 1110 that receives slurryfrom separator 1012, and a pumping system 1112 that pumps slurry frombasin 1110 to separator 1022. System 1100 operates the same as system1000 except that once-screened slurry 1042 output by separator 1012 isgravity fed into basin 1110, and pumping system 1112 then pumpsonce-screened slurry 1042 into separator 1022. Basin 1110 can be madequite small if slurry is pumped into separator 1022 before pumpingsystem 1014 stops pumping slurry from basin 1010.

[0071] When reused for flushing, experimental results have indicatedthat the use of twice-screened slurry 1044 has a scrubbing effect thattends to clean the flushed areas. In addition, recycling and reusingtwice-screened slurry 1044 significantly minimizes the amount of freshwater that needs to be introduced into the flushing system.

[0072] Experimental results taken from twice-screened slurry 1044indicate that the use of separators 1012 and 1022 removes 90% and moreof the solids from slurry 1040. This is in stark contrast to the 16% ofthe solids that are removed by prior-art separator 100. One benefit ofthis dramatic increase in the percentage of removed solids is that theuseful life of the lagoons is significantly extended.

[0073] Another benefit is that if slurry 1040 is processed within a fewhours after being collected, the amount of nutrients and salts that areloaded into twice-screened slurry 1044 is significantly reduced.Experimental results indicate that twice-screened slurry 1044 hasnitrogen levels that are about twice the levels of normal cow manure, adramatic reduction in the amount of nitrogen that is present inunscreened slurry taken from a settling lagoon.

[0074] It should be understood that various alternatives to the methodof the invention described herein may be employed in practicing theinvention. For example, although openings 316 and 318 (and 710) are showas formed in side walls 312 and 314, respectively, openings 316 and 318(and 710) can be formed in any vertical surface that forms a part of theoutflow compartment, such as back wall 310.

[0075] Further, rather than using openings 316 and 318, a single openingcan alternately be used. Thus, it is intended that the following claimsdefine the scope of the invention and that methods and structures withinthe scope of these claims and their equivalents be covered thereby.

What is claimed is:
 1. A separator comprising: an input compartmenthaving an input opening and an output ledge, a manure slurry beingpumped into the input compartment through the input opening, and flowingout over the output ledge; a sloped screen connected to the output ledgeof the input compartment, the sloped screen having a plurality of screenopenings, the screen openings having a size that ranges from a lowersize to an upper size, the lower size being greater than a size thatrequires shaking before the manure slurry will fall through the screenopenings, the upper size being equal to or less than 1.0 mm, the manureslurry flowing out over the output ledge onto the sloped screen when themanure slurry is pumped into the input compartment; and a collectioncompartment connected to the sloped screen, the collection compartmenthaving an air flow opening and a slurry exit opening, and receiving ascreened slurry that falls through the sloped screen when the manureslurry is pumped into the input compartment, the screened slurry flowingout through the slurry exit opening.
 2. The separator of claim 1 andfurther comprising: a water pipe connected to the collection compartmentthat extends across the sloped screen; and a plurality of spray headsconnected to the water pipe, the spray heads outputting a liquid at arate, the rate being greater than seventy liters per hour, and less thanone thousand liters per hour.
 3. The separator of claim 2 and furthercomprising an air flow controller connected to the collectioncompartment, the air flow controller controlling a first volume of airthat flows through the sloped screen as a result of the screened slurryflowing through the slurry exit opening.
 4. The separator of claim 3wherein the air flow controller variably controls a second volume of airthat can flow into the air flow opening to thereby vary the first volumeof air that is pulled through the sloped screen.
 5. The separator ofclaim 4 wherein the input compartment includes a baffle that insuresthat the manure slurry flows evenly across the output ledge.
 6. Theseparator of claim 1 wherein the upper size is equal to or less than0.89 mm.
 7. The separator of claim 6 and further comprising: a waterpipe connected to the collection compartment that extends across thesloped screen; and a plurality of spray heads connected to the waterpipe, the spray heads outputting a liquid at a rate, the rate beinggreater than seventy liters per hour, and less than one thousand litersper hour.
 8. The separator of claim 7 and further comprising an air flowcontroller connected to the collection compartment, the air flowcontroller controlling a first volume of air that flows through thesloped screen as a result of the screened slurry flowing through theslurry exit opening.
 9. The separator of claim 8 wherein the air flowcontroller variably controls a second volume of air that can flow intothe air flow opening to thereby vary the first volume of air that ispulled through the sloped screen.
 10. The separator of claim 9 whereinthe input compartment includes a baffle that insures that the manureslurry flows evenly across the output ledge.
 11. The separator of claim1 wherein the upper size is equal to or less than 0.64 mm.
 12. Theseparator of claim 11 and further comprising: a water pipe connected tothe collection compartment that extends across the sloped screen; and aplurality of spray heads connected to the water pipe, the spray headsoutputting a liquid at a rate, the rate being greater than seventyliters per hour, and less than one thousand liters per hour.
 13. Theseparator of claim 12 and further comprising an air flow controllerconnected to the collection compartment, the air flow controllercontrolling a first volume of air that flows through the sloped screenas a result of the screened slurry flowing through the slurry exitopening.
 14. The separator of claim 13 wherein the air flow controllervariably controls a second volume of air that can flow into the air flowopening to thereby vary the first volume of air that is pulled throughthe sloped screen.
 15. The separator of claim 14 wherein the inputcompartment includes a baffle that insures that the manure slurry flowsevenly across the output ledge.
 16. A separator comprising: an inputcompartment having an input opening and an output opening; a slopedscreen connected to the output opening of the input compartment, thesloped screen having a plurality of screen openings, the screen openingshaving a size that ranges from equal to or greater than about 0.18 mm toequal to or less than 1.0 mm; and a collection compartment connected tothe sloped screen, the collection compartment having an air flow openingand a slurry exit opening.
 17. The separator of claim 16 and furthercomprising: a water pipe connected to the collection compartment thatextends across the sloped screen; and a plurality of spray headsconnected to the water pipe, the spray heads outputting a liquid at arate, the rate being greater than seventy liters per hour, and less thanone thousand liters per hour.
 18. The separator of claim 17 and furthercomprising an air flow controller connected to the collectioncompartment, the air flow controller controlling a first volume of airthat flows through the sloped screen.
 19. The separator of claim 18wherein the air flow controller variably controls a second volume of airthat can flow into the air flow opening to thereby vary the first volumeof air that is pulled through the sloped screen.
 20. The separator ofclaim 16 wherein the screen openings have a size that ranges from about0.18 mm to equal to or less than 1.0 mm.
 21. The separator of claim 20and further comprising: a water pipe connected to the collectioncompartment that extends across the sloped screen; and a plurality ofspray heads connected to the water pipe, the spray heads outputting aliquid at a rate, the rate being greater than seventy liters per hour,and less than one thousand liters per hour.
 22. The separator of claim21 and further comprising an air flow controller connected to thecollection compartment, the air flow controller controlling a firstvolume of air that flows through the sloped screen.
 23. The separator ofclaim 22 wherein the air flow controller variably controls a secondvolume of air that can flow into the air flow opening to thereby varythe first volume of air that is pulled through the sloped screen. 24.The separator of claim 16 wherein the screen openings have a size thatranges from about 0.18 mm to equal to or less than 0.89 mm.
 25. Theseparator of claim 24 and further comprising: a water pipe connected tothe collection compartment that extends across the sloped screen; and aplurality of spray heads connected to the water pipe, the spray headsoutputting a liquid at a rate, the rate being greater than seventyliters per hour, and less than one thousand liters per hour.
 26. Theseparator of claim 25 and further comprising an air flow controllerconnected to the collection compartment, the air flow controllercontrolling a first volume of air that flows through the sloped screen.27. The separator of claim 26 wherein the air flow controller variablycontrols a second volume of air that can flow into the air flow openingto thereby vary the first volume of air that is pulled through thesloped screen.
 28. The separator of claim 16 wherein the screen openingshave a size that ranges from about 0.18 mm to equal to or less than 0.64mm.
 29. The separator of claim 16 wherein the screen openings have asize that ranges from equal to or greater than 0.18 mm to equal to orless than 0.89 mm.
 30. The separator of claim 16 wherein the screenopenings have a size that ranges from equal to or greater than 0.18 mmto equal to or less than 0.64 mm.
 31. A separator comprising: an inputcompartment having an input opening and an output ledge, a manure slurrybeing pumped into the input compartment through the input opening, andflowing out over the output ledge; a sloped screen connected to theoutput ledge of the input compartment, the sloped screen having aplurality of screen openings and a width, the manure slurry flowing outover the output ledge onto the sloped screen when the manure slurry ispumped into the input compartment; a collection compartment connected tothe sloped screen, the collection compartment having an air flow openingand a slurry exit opening, and receiving a screened slurry that fallsthrough the sloped screen when the manure slurry is pumped into theinput compartment, the screened slurry flowing out through the slurryexit opening; a water pipe connected to the collection compartment thatextends across the sloped screen; and a plurality of spray headsconnected to the water pipe, the spray heads outputting a liquid at arate, the rate ranging from equal to or greater than 113 liters per hourto equal to or less than 1362 liters per hour per approximately 0.31meters of the width.
 32. The separator of claim 31 and furthercomprising an air flow controller connected to the collectioncompartment, the air flow controller controlling a first volume of airthat flows through the sloped screen as a result of the screened slurryflowing through the slurry exit opening.
 33. The separator of claim 32wherein the air flow controller variably controls a second volume of airthat can flow into the air flow opening to thereby vary the first volumeof air that is pulled through the sloped screen.
 34. A separatorcomprising: an input compartment having an input opening and an outputopening, a manure slurry being pumped into the input compartment throughthe input opening, and flowing out through the output opening; a slopedscreen connected to the output opening of the input compartment, thesloped screen having a plurality of screen openings and a width, themanure slurry flowing out over the output opening onto the sloped screenwhen the manure slurry is pumped into the input compartment; acollection compartment connected to the sloped screen, the collectioncompartment having an air flow opening and a slurry exit opening, andreceiving a screened slurry that falls through the sloped screen whenthe manure slurry is pumped into the input compartment, the screenedslurry flowing out through the slurry exit opening; and an air flowcontroller connected to the collection compartment, the air flowcontroller controlling a first volume of air that flows through thesloped screen as a result of the screened slurry flowing through theslurry exit opening.
 35. The separator of claim 34 wherein the air flowcontroller variably controls a second volume of air that can flow intothe air flow opening to thereby vary the first volume of air that ispulled through the sloped screen.
 36. The separator of claim 35 andfurther comprising: a water pipe connected to the collection compartmentthat extends across the sloped screen; and a plurality of spray headsconnected to the water pipe, the spray heads outputting a liquid at arate, the rate ranging from equal to or greater than 113 liters per hourto equal to or less than 1362 liters per hour per approximately 0.31meters of the width.
 37. A separator comprising: an input compartmenthaving an input opening and an output opening; a sloped screen connectedto the output opening of the input compartment, the sloped screen havinga plurality of screen openings, the screen openings having a size thatranges from equal to or greater than about 0.23 mm to equal to or lessthan 0.89 mm; and a collection compartment connected to the slopedscreen, the collection compartment having an air flow opening and aslurry exit opening.
 38. The separator of claim 37 wherein the screenopenings have a size that ranges from about 0.23 mm to equal to or lessthan 0.64 mm.
 39. The separator of claim 37 wherein the screen openingshave a size that ranges from equal to or greater than 0.23 mm to equalto or less than 0.64 mm.